Getting the most out of MRI in perianal fistula: update on surgical techniques and radiological features that define surgical options.

Perianal fistulas affect approximately 2 in 10,000 people, causing symptoms such as pain and discharge, which can have a debilitating effect on a patient's quality of life. Surgical treatment, which can offer a potential cure or palliation of symptoms, must be considered carefully in cases with extensive sphincter involvement. In complex cases, the use of preoperative magnetic resonance imaging (MRI) can help to determine the best course of operative action. This review describes common and contemporary surgical procedures for perianal fistula, highlighting technical features, as well as important surgical considerations associated with each method and how these can be assessed radiologically. We focus on the anatomical features and MRI findings that take procedural elements into account and help determine the most appropriate method of treatment. The aim of this article is to provide a basis for informed and focused discussion between surgeons and radiologists to ensure the most appropriate procedure is selected for each case, with the ultimate aim of obtaining the most favourable outcomes for patients.

Heterogeneity in outcome selection, definition and measurement in studies assessing the treatment of cryptoglandular anal fistula: findings from a systematic review.

BACKGROUND: Treatment for cryptoglandular anal fistula (AF) is challenging and a lack of uniform outcomes in the literature prevents direct comparison of treatments. This can be addressed by developing a core outcome set, a standardised set of outcomes reported in all interventional studies for a specific condition. The aim of this systematic review is to assess the range of outcomes, their definitions, and the measurement instruments currently utilised in interventional studies for adult patients with AF. This will inform the development of an AF core outcome set. METHODS: Medline, Embase and The Cochrane Library were searched to identify all patient- and clinician-reported outcomes in studies assessing medical, surgical or combination treatment of adult patients with AF published from January 2008 to May 2020. The resulting outcomes were categorized according to the Core Outcome Measurement in Effectiveness Trials (COMET) taxonomy to better understand their distribution. RESULTS: In total, 155 studies were included, 552 outcomes were extracted, with a median of three outcomes (interquartile range 2-5) per study. Only 25% of studies demonstrated high-quality outcome reporting. The outcomes were merged into 52 unique outcomes and structured into four core areas and 14 domains, with the majority in the domain of physiological or clinical (gastrointestinal) outcomes. The most commonly reported outcomes were healing (77%), incontinence (63%), and recurrence (40%), with no single outcome assessed across all studies. There was a wide variation in outcome definitions and measurement instruments used. CONCLUSIONS: There is substantial heterogeneity in outcomes, definitions, and measurement instruments reported in interventional studies for cryptoglandular anal fistula. This emphasises the need for standardised outcome reporting and measurement.

Perianal fistula and the ileoanal pouch - different aetiologies require distinct evaluation.

AIM: Restorative proctocolectomy has been widely adopted as the procedure of choice for restoring gastrointestinal continuity following proctocolectomy. It is often associated with improved quality of life and high patient satisfaction; however, the development of a pouch anal fistula can cause significant morbidity. Pouch fistulas are notoriously difficult to treat and there is great heterogeneity in the management reported of these fistulas. A lack of classification, and the assumption that fistulas originating from completely different aetiologies will behave and respond similarly to a particular treatment strategy, precludes meaningful comparison of management outcomes. We aim to introduce consistency in the reporting of pouch fistulas using a novel classification system. METHODS: A consensus process involving clinicians experienced in the management of pouch fistulas from two high volume tertiary centres was performed. RESULTS: We propose that pouch anal fistulas should be classified into four distinct groups according to their aetiology: group 1, anastomotic related; group 2, inflammatory bowel disease related, with sub-classifications Crohn's (type A) and non-Crohn's (type B) in origin; group 3, cryptoglandular related; and group 4, malignancy related. CONCLUSION: Classification of pouch fistulas according to their aetiology will provide consistency in the literature and improve the quality of prospective evidence for the management of pouch fistulas.

The development of a cryptoglandular Anal Fistula Core Outcome Set (AFCOS): an international Delphi study protocol.

PURPOSE: Cryptoglandular anal fistula is a disorder with an incidence of around 1 per 5,000 people per year in European countries. Many studies have been conducted to evaluate the effectiveness of interventions for anal fistula. However, there is considerable heterogeneity in the outcomes assessed and reported in these studies. This limits research quality and complicates evidence synthesis. A solution for heterogeneity in outcome reporting is the development of a Core Outcome Set (COS). This paper describes the protocol for the development of a European COS for Anal Fistula (AFCOS). METHODS: The first step will be a systematic review of the literature to identify potential outcomes that may be included in the COS. Patient interviews will be conducted in The United Kingdom and The Netherlands to ensure that both clinician-important and patient-important outcomes are captured. The outcomes will be categorized using the COMET taxonomy and taken forward to a Delphi consensus exercise. In up to three web-based Delphi surveys the outcomes will be prioritized by patients, clinicians (surgeons, gastroenterologists, and radiologists), and (clinical) researchers. The responses will be summarized and reported anonymously in subsequent round(s) facilitating convergence to a consensus opinion. The final COS will be decided during a face-to-face consensus meeting with patients, clinicians, and (clinical) researchers. DISCUSSION: This study protocol describes the development of a European COS for anal fistula to improve research quality, evidence synthesis, and patient care.

Systematic review and meta-analysis of endorectal advancement flap and ligation of the intersphincteric fistula tract for cryptoglandular and Crohn's high perianal fistulas.

Background: High perianal fistulas require sphincter-preserving surgery because of the risk of faecal incontinence. The ligation of the intersphincteric fistula tract (LIFT) procedure preserves anal sphincter function and is an alternative to the endorectal advancement flap (AF). The aim of this study was to evaluate outcomes of these procedures in patients with cryptoglandular and Crohn's perianal fistulas. Methods: A systematic literature search was performed using MEDLINE, Embase and the Cochrane Library. All RCTs, cohort studies and case series (more than 5 patients) describing one or both techniques were included. Main outcomes were overall success rate, recurrence and incontinence following either technique. A proportional meta-analysis was performed using a random-effects model. Results: Some 30 studies comprising 1295 patients were included (AF, 797; LIFT, 498). For cryptoglandular fistula (1098 patients), there was no significant difference between AF and LIFT for weighted overall success (74·6 (95 per cent c.i. 65·6 to 83·7) versus 69·1 (53·9 to 84·3) per cent respectively) and recurrence (25·6 (4·7 to 46·4) versus 21·9 (14·8 to 29·0) per cent) rates. For Crohn's perianal fistula (64 patients), no significant differences were observed between AF and LIFT for overall success rate (61 (45 to 76) versus 53 per cent respectively), but data on recurrence were limited. Incontinence rates were significantly higher after AF compared with LIFT (7·8 (3·3 to 12·4) versus 1·6 (0·4 to 2·8) per cent). Conclusion: Overall success and recurrence rates were not significantly different between the AF and LIFT procedure, but continence was better preserved after LIFT.

Review article: pathogenesis of Crohn's perianal fistula-understanding factors impacting on success and failure of treatment strategies.

BACKGROUND: Evidence from groups who have studied fistula aetiology and extrapolation from interventional studies supports a multifactorial hypothesis of Crohn's perianal fistula, with several pathophysiological elements that may contribute to fistula formation, persistence and resistance to treatment. AIM: An evidence synthesis of current understanding of pathophysiological factors underlying Crohn's perianal fistula is presented, exploring the fundamental reasons why some treatments succeed and others fail, as a means of focussing clinical knowledge on improving treatment of Crohn's perianal fistula. METHODS: Evidence to support this review was gathered via the Pubmed database. Studies discussing pathophysiological factors underpinning perianal fistula, particularly in Crohn's disease, were reviewed and cross-referenced for additional reports. RESULTS: Pathophysiological factors that impact on success or failure of interventions for Crohn's perianal fistulae include the high-pressure zone, obliterating the dead space, disconnecting the track from the anus, removing epithelialisation, eradicating sepsis and by-products of bacterial colonisation, correcting abnormalities in wound repair and removing the pro-inflammatory environment which allows fistula persistence. Most current interventions for Crohn's perianal fistulae tend to focus on a single, or at best two, aspects of the pathophysiology of Crohn's anal fistulae; as a result, failure to heal fully is common. CONCLUSIONS: For an intervention or combination of interventions to succeed, multiple factors must be addressed. We hypothesise that correct, timely and complete attention to all of these factors in a multimodal approach represents a new direction that may enable the creation of an effective treatment algorithm for Crohn's anal fistula.

Short-term efficacy and safety of three novel sphincter-sparing techniques for anal fistulae: a systematic review.

BACKGROUND: The surgical treatment of complex anal fistulae, particularly those involving a significant portion of the anal sphincter in which fistulotomy would compromise continence, is challenging. Video-assisted anal fistula treatment (VAAFT), fistula tract laser closure (FiLaC™) and over-the-scope clip (OTSC®) proctology system are all novel sphincter-sparing techniques targeted at healing anal fistulae. In this study, all published articles on these techniques were reviewed to determine efficacy, feasibility and safety. METHODS: A systematic search of major databases was performed using defined terms. All studies reporting on experience of these techniques were included and outcomes (fistula healing and safety) evaluated. RESULTS: Eighteen studies (VAAFT-12, FiLaC™-3, OTSC®-3) including 1245 patients were analysed. All were case series, and outcomes were heterogeneous with follow-up ranging from 6 to 69 months and short-term (< 1 year) healing rates of 64-100%. Morbidity was low with only minor complications reported. There was one report of minor incontinence following the first reported study of FiLaC™, and this was treated successfully at 6 months with rubber band ligation of hypertrophied prolapsed mucosa. There are inconsistencies in the technique in studies of VAAFT and FiLaC™. CONCLUSIONS: All three techniques appear to be safe and feasible options in the management of anal fistulae, and short-term healing rates are acceptable with no sustained effect on continence. There is, however, a paucity of robust data with long-term outcomes. These techniques are thus welcome additions; however, their long-term place in the colorectal surgeon's armamentarium, whether diagnostic or therapeutic, remains uncertain.

Natural history of anorectal sepsis.

BACKGROUND: Progression from anorectal abscess to fistula is poorly described and it remains unclear which patients develop a fistula following an abscess. The aim was to assess the burden of anorectal abscess and to identify risk factors for subsequent fistula formation. METHODS: The Hospital Episode Statistics database was used to identify all patients presenting with new anorectal abscesses. Cox regression analysis was undertaken to identify factors predictive of fistula formation. RESULTS: A total of 165 536 patients were identified in the database as having attended a hospital in England with an abscess for the first time between 1997 and 2012. Of these, 158 713 (95·9 per cent) had complete data for all variables and were included in this study, the remaining 6823 (4·1 per cent) with incomplete data were excluded from the study. The overall incidence rate of abscess was 20·2 per 100 000. The rate of subsequent fistula formation following an abscess was 15·5 per cent (23 012 of 148 286) in idiopathic cases and 41·6 per cent (4337 of 10 427 in patients with inflammatory bowel disease (IBD) (26·7 per cent coded concurrently as ulcerative colitis; 47·2 per cent coded as Crohn's disease). Of all patients who developed a fistula, 67·5 per cent did so within the first year. Independent predictors of fistula formation were: IBD, in particular Crohn's disease (hazard ratio (HR) 3·51; P < 0·001), ulcerative colitis (HR 1·82; P < 0·001), female sex (HR 1·18; P < 0·001), age at time of first abscess 41-60 years (HR 1·85 versus less than 20 years; P < 0·001), and intersphincteric (HR 1·53; P < 0·001) or ischiorectal (HR 1·48; P < 0·001) abscess location compared with perianal. Some 2·9 per cent of all patients presenting with a new abscess were subsequently diagnosed with Crohn's disease; the median time to diagnosis was 14 months. CONCLUSION: The burden of anorectal sepsis is high, with subsequent fistula formation nearly three times more common in Crohn's disease than idiopathic disease, and female sex is an independent predictor of fistula formation following abscess drainage. Most fistulas form within the first year of presentation with an abscess.

What role do bacteria play in persisting fistula formation in idiopathic and Crohn's anal fistula?

AIM: The aetiology of Crohn's disease-related anal fistula remains obscure. Microbiological, genetic and immunological factors are thought to play a role but are not well understood. The microbiota within anal fistula tracts has never been examined using molecular techniques. The present study aimed to characterize the microbiota in the tracts of patients with Crohn's and idiopathic anal fistula. METHOD: Samples from the fistula tract and rectum of patients with Crohn's and idiopathic anal fistula were analysed using fluorescent in situ hybridization, Gram staining and scanning electron microscopy were performed to identify and quantify the bacteria present. RESULTS: Fifty-one patients, including 20 with Crohn's anal fistula, 18 with idiopathic anal fistula and 13 with luminal Crohn's disease and no anal fistula, were recruited. Bacteria were not found in close association with the luminal surface of any of the anal fistula tracts. CONCLUSION: Anal fistula tracts generally do not harbour high levels of mucosa-associated microbiota. Crohn's anal fistulas do not seem to harbour specific bacteria. Alternative explanations for the persistence of anal fistula are needed.

Seven-year experience of enterocutaneous fistula with univariate and multivariate analysis of factors associated with healing: development of a validated scoring system.

AIM: The management of enterocutaneous fistulae (ECF) is complex and challenging. We examined factors associated with fistula healing at a National Intestinal Failure Centre and devised the first scoring system to predict spontaneous fistula healing prior to surgery. METHOD: A retrospective audit of 177 patients (mean age 48.7 years) treated over 7 years was undertaken. Results were compared with a previously reported series from this unit. Univariate and multivariate analyses wete performed on variables to assess relationship with ECF healing. A scoring system was devised and validated on a prospective cohort. RESULTS: One-hundred and fifty patients underwent surgery between January 2003 and December 2009. The overall healing rate following surgery in the current series was 94.6% (82% in the previous series). Mean delay from previous surgery to the current operation was 1 year (compared with 8 months previously). Thirty-day postfistula resection mortality was 0% (compared with 3.5% previously). Twenty-seven patients underwent medical management alone with overall healing rate of 46.4% (vs 19.9%). Multivariate analysis revealed that comorbidity (P = 0.02), source of referral (P = 0.01) and aetiology (P = 0.006) had associations with healing. Almost all patients with scores of 0 and 1 healed, whereas the highest scores healed least frequently. CONCLUSION: Surgical management of ECF is safe and improving. Fistula healing is affected by aetiology, comorbidity and source of referral. The scoring system has the potential to predict ECF healing and can be a useful clinical decision-making tool.

Surgical management of rectovaginal fistula in a tertiary referral centre: many techniques are needed.

AIM: Surgery is the mainstay of treatment for rectovaginal fistula (RVF). Published success rates vary with initial success being around 50% rising to 80% with repeated surgery. Fistulae in Crohn's disease are more likely to recur. METHOD: A retrospective study was performed of RVF repair carried out between 2003 and 2008 in a tertiary referral centre. Patients undergoing surgery for an RVF under the senior author during the study period were identified and their clinical notes were reviewed. RESULTS: Thirty-five patients underwent 50 operations. The median age was 42 years and 83% were tertiary referrals. Two patients were lost to follow-up. Healing occurred in 19 (58%) of 33 patients after a mean of 1.4 operations. The median time to success was 11 (2.5-48) months. The 'curative' group had an overall success of 73% (19 of 26). Seventy-five per cent of non-inflammatory bowel disease patients and 67% of those with Crohn's disease had successful treatment of the RVF. Twenty-four of 35 patients (67%) underwent creation of a stoma. Sixteen of 24 (67%) were deemed fit for restoration of continuity. No demographic or disease related factors were found to influence healing. CONCLUSION: Cure of RVF can be achieved by a range of surgical approaches including abdominal and anal. A variety of different anal techniques are necessary, depending on the integrity of the anal sphincter and the presence or absence of perineal descent/internal intussusception.

Review article: medical, surgical and radiological management of perianal Crohn's fistulas.

BACKGROUND: Crohn's anal fistulas are common and cause considerable morbidity. Their management is often difficult; medical and surgical treatments rarely lead to true healing with frequent recurrence and complications. AIM: To examine medical treatments previously and currently used, surgical techniques and the important role of optimal imaging. METHODS: We conducted a literature search in the Pub Med database using Crohn's, Anal Fistula, Surgery, Imaging and Medical Treatment as search terms. RESULTS: Antibiotics and immunosuppressants have a role, but slow initial response, side effects and relatively low remission rates of up to around a third with frequent recurrence limit their value. Long-term infliximab produces clinical remission in 36-58% of patients with combined medical and surgical management achieving optimal outcomes. Traditional and newer surgical procedures often have a high rate of recurrence with a significant risk of temporary or, in up to 10% of cases, permanent stomas, incontinence and unhealed or slowly healing wounds in 30%. CONCLUSIONS: Management of Crohn's anal fistulas remains challenging. Established principles are to drain infection, use setons as required, aggressively manage active proctitis, give antibiotics, immunosuppressants and employ anti-TNFα therapy, and they demand significant co-operation between gastroenterologists and surgeons.